[Relax][Backend] Fix TVM crashes with default relax pipeline when opt_level=1: InternalError: Check failed: (slot->value_computed) is false

[cchung100m]

Hi Commiters,

This PR is trying to fix issues https://github.com/apache/tvm/issues/17876. Any suggestions would be appreciated if you are available.

Root Cause

VMShapeLower crashed when processing ShapeExpr containing composite PrimExpr that weren't computed yet.

Solution

~~Modified VisitExpr_(const ShapeExprNode* op) in vm_shape_lower.cc to:~~

~~1. Mark uncomputed variables as ready for computation~~ ~~2. Trigger EmitOutstandingPrimExprCompute() to resolve the dependency chain~~ ~~3. Ensure all expressions are computed before calling MakeSymbolicShapeArg~~

~~Added test case: test_composite_shape_expression_fix() to prevent future occurrences.~~

symbolizing the composite PrimExpr in the pipeline: canonicalization